They’re very pretty and typical of Maine winters, but if you’ve got icicles, then you’ve got an ice dam.
An ice dam is caused by heat leaking into the attic and getting trapped under the roof deck. This causes excessive melting of snow, which runs down the roof plane until it gets to the eve. Obviously the eve will be slightly colder since it typically extends outside the house. Once the water hits the colder eve area, ice starts to form, and it builds up and dams the snow melt. Icicles are a sure sign of ice dams. Water backs up, and can leak into your home, damaging ceilings, walls and insulation. The prevention is air sealing the attic and proper venting of that accumulated heat.
It’s easier to prevent an ice dam than to fix one! You will probably need to call a professional for some parts of ice dam prevention, like adding insulation and keeping the roof clear of snow, but there are some easy ways you can keep warm air out of the attic.
How to prevent an ice dam
- Make sure your eve and ridge vents are clear, so that the roof is venting properly (warm air that makes it to the roof is being vented before it causes snow to melt.)
- Keep warm air from getting into your attic! Shut the doors to unused rooms upstairs, and make sure the attic door or entry way is insulated as well, and that any air leaks are sealed. Adding a blanket barrier to the attic door might help.
- Insulate the attic floor, or add additional insulation if needed.
- Don’t overlook kneewalls.
- Invest in a snowrake and keep your roof as clear as you can. Eliminating the snowpack to cut down on melting will ease the problem.
How to fix an ice dam
You’ll almost certainly want help. Be wary of strangers offering to shovel your roof. It’s dangerous work, and any damage to the roof (or the shoveler!) may be hard and expensive to repair. Consider hiring a professional.
- Check eve and ridge vents to make sure they are unobstructed.
- Remove the source of moisture the best you can (snow on roof)
- Expose the ice dam
- Try gently tapping (not chopping) the ice to break it up. Most folks cause more damage (which the insurance company will deny) chopping ice and damaging the shingles. The object is to get the water to drain, and to keep it draining. Rock salt can help!
- Take pictures of everything and notify your insurance carrier as it’s covered under a normal homeowner’s policy.
You may also want to:
- Try to get at any saturated insulation and/or building materials above the damaged ceiling and remove them if possible. This might mean a rip to the attic, or actually removing a small section of damaged sheetrock ceiling since that will allow air circulation and it’s going to need replacement anyway.
- Dry out the wet building materials the best you can. Remember that cold air circulating has almost no moisture carrying capacity so don’t waste your time circulating (i.e. fans) cold air.
- Replace moldy or damaged insulation if necessary
Obviously, you won’t want to do any repairs until you’re sure the roof won’t leak again. That’s where it may help to have professionals assess what you need to do to tighten up the house and keep the warm air out of the attic. The University of Minnesota Extension Service (where they get a lot of snow, like Maine!) has a good descriptive page on ice dams.
